If you’ve ever asked yourself that question, I’m here to try to answer that for you with a little help from Google. Google has done a great job of doing this work for you, they have a nice “heat map” of what areas of a webpage perform the best with advertisements. But keep in mind different things will work for different sites. Personally I have found that on a blog where a lot of people comment I have good luck placing a 250×250 ad right below the article on the article landing page (not the homepage). So the ad is placed between the end of the article and the comment box. This works well if you get a lot of comments as people will finish the article and be right there to click on your ad. Just make sure those ads pertain to what the site is about or people won’t even look twice.
I have also read that the upper left hand section of a page is what is looked at most. This is usually where a company or website’s logo is found, but if that is the most looked at part of the site I say put an ad up there or at least put an ad underneath your logo. Nothing too big and obtrusive though, it will just push people away.
Take a look at the “heat map” that Google provides.
This shows that the best placement for ads is directly above the content on the webpage, in the middle. The darker the orange box the better the placement for ads. So as you can see ads that are placed above the “fold” (what the user sees before having to scroll down) usually perform a lot better than ads placed towards the bottom of the page. And the obvious emphasis is on the left had side of the page, so this is where you should focus your highest paying ads to if you’re using an affiliate program and if you’re using adsense, just put the code over there somewhere.
As I mentioned above this may not be the best placement for ALL sites, so make sure you experiment with where your ads are placed on a page and find out what works best for you. Most of the publisher programs like adsense, have the ability to track specific ad units that you place on your page, so make sure you utilize those to determine exactly which ads are getting you the most clicks so you don’t change something that was doing well.